The Supreme Court of Canada handed down twinjudgments Friday that back key elements of the provincial government’s policy after it was challenged by motorists.

Justices said there was “no doubt” automatic roadside prohibitions are within the province’s jurisdiction and a valid regulatory measure.

They rejected the argument of opponents that the penalties effectively create an offence that requires a right to a fair trial, not an instant decision by police after a failed blood-alcohol reading on a portable device.

The court found the province’s “pressing and substantial” goal of enacting the scheme “was not to oust the criminal law, but rather to prevent death and serious injury on public roads by removing drunk drivers and deterring impaired driving.”

Roadside penalties have largely supplanted criminal investigations and prosecutions for impaired driving in B.C. The amount of time and money expended on drunk driving cases in the courts and by police is down because of the nearly 70 per cent drop in impaired charges.

Police still pursue criminal charges in cases of injury or death due to drunk driving.

Defence lawyers have criticized the immediate roadside prohibitions as a de facto decriminalization of most cases of impaired driving.

Although drivers who are caught and punished at roadside face stiff sanctions, they do not usually risk an impaired driving conviction and criminal record.

Also before the courts was the constitutionality of the compulsory demand to provide a breath sample or face roadside penalties.

A majority of Supreme Court justices said the original 2010 provision did violate the Charter of Rights protection against unlawful search and seizure.

The province amended its law in 2012 to allow drivers who fail a roadside breath test to take a second test – the lowest of the two readings is used – and created a process for them to appeal driving prohibitions.

“Our belief is that the amendments our government made in June 2012 already address the constitutional issues noted in the court’s decision,” B.C. Justice Minister Suzanne Anton said.

It’s not yet clear if drivers penalized in the first two years of the program could be compensated.

Anton welcomed the ruling, adding immediate roadside prohibitions have been “very effective” and have saved an estimated 260 lives over the past five years.

“People are learning from them, they’re not drinking and driving as much,” Anton said. “As soon as you blow that warn or that fail you will be penalized. And that is what deters people from drinking and driving. That’s what keeps our roads safe.”

Defence lawyers intend to continue to challenge elements of the B.C. law that were not addressed by the top court.

About 18,000 roadside prohibitions are issued each year and about two per cent are successfully challenged through the review process.